Electron tube mount and method of making the same



Nov. 22, 1966 J. A. GAUSZ 3,237,080

ELECTRON TUBE MOUNT AND METHOD OF MAKING THE SAME Filed June 27, 1963 II I I I I 4 I 5 I INVENTOR .ffl/m/ A 641/52 -fl, d4 how United StatesPatent 3,287,080 ELECTRON TUBE MOUNT AND METHOD OF MAKING THE SAME JohnAlexander Gausz, Watchung, NJ., assignor to Radio Corporation ofAmerica, a corporation of Delaware Filed June 27, 1963, Ser. No. 291,084

15 Claims. (Cl. 3162) The present invention relates to electron tubemounts and to a method of making such mounts, and also to a method ofsalvaging mounts when one or more parts thereof have been damaged duringassembly.

The invention is particularly advantageous in connection with themanufacture of a receiving type electron tube having a cathode-heaterstructure comprising a tubular cathode having a folded insulated heatertherein, and an insulated helical spacer member disposed between theheater and cathode for increasing the insulation between the cathode andheater beyond that provided by the insulating coating on the heater. Theinsulation on the helical spacing member thus supplements the insulationprovided by the coating on the heater for effectively electricallyisolating the heater from the cathode. This is of particular advantagewhen the cathode and heater are operated at a relatively large voltagedifference, such as in high voltage rectifiers.

In the manufacture of one kind of high voltage half wafer rectifier, atubular anode and a tubular cathode are first assembled in concentricrelation and mounted between and supported by two insulating wafers toprovide an electrode cage. As a separate operation, an insulated foldedheater is threaded through or inserted into an insulated helical spacingmember, to provide a heaterspacer assembly. In the heater-spacerassembly, adjacent end portions thereof are bare of insulation for laterfixing as by welding to lead-in wires of a stem. The heater wire isrelatively thin so that the bare end portions or legs thereof can bedeflected to appropriate ones of the lead-in wires. However, the wire ofwhich the insulated spacer member is made, is relatively thick and rigidso that it cannot be readily deflected. In view of this difliculty indeflecting the bare portion of the spacer member, a desired bend thereinis provided during formation of the spacer member to helical shape.After the heater is inserted into the spacer the heater-spacer assemblyso formed is threaded into the cathode from the cathode end that iseventually to be adjacent to the stem in the finished mount. Theelectrode cage, with the heater-spacer within the cathode of the cage,and with bare end portions or legs of the heater and spacer extendingfrom one end of the cage, is then mounted on a stem with the bare endportions referred to adjacent to the stem. When so mounted, ears of ananode of the cage engage one or more of the lead-in wires in the stem,to which they are then welded. A tab extending from the cathode is bentto engage another of the lead-ins and is welded thereto. In like manner,the flexible bare heater legs are deflected to engage others of thelead-ins and are welded thereto. The spacer member is then rotatedwithin the cathode to dispose its previously bent bare end portion inengagement with a selected stud, or inner stem lead, to which it is thenwelded.

The stud and the lead-in wires in the stern are disposed in a circulararray of larger radius than the cathode, and the bent bare end portionof the spacer extends laterally beyond an axial projection of thecathode. This lateral extension of the spacer places a limitation on themanner in which the heater-spacer assembly can be threaded into thecathode. Thus, the heater-spacer assembly can be threaded into thecathode only from the end thereof that eventually is to be adjacent tothe stem in a finished mount. This limitation has heretofore precluded asalvaging of the mount parts when the heater or spacer are damaged as byloss of insulation.

Such loss of insulation is likely to occur as a consequence ofengagement of the coated portions of the heater and spacer with arelatively sharp edge defining the cathode end from which the bare endportions of the heater and spacer protrude. Such engagement (occurringin rotating the spacer for engagement with its associated stud,deflecting the heater legs into contact with their respective lead-ins,and in the application of a force to these elements during the severalwelding operations), often causes chipping and loss of insulation fromthe heater and/or spacer at portions thereof adjacent to the cathode.

Once such loss of insulation has occurred, which can be determined by avisual inspection of a mount, it has heretofore been necessary to scrapat least a major part of the entire mount. This is a consequence of thefact that it is not readily feasible to separate an electrode cage froma stem to which it has been fixed, to permit substitution of a newheater-spacer assembly for the damaged one.

Such separation requires severance of elements that would irreparablydamage the separated cage and stem and preclude their use in a repairedmount. One area where such severance would be particularly objectionableis that which involves the welded connection of one or more lead-ins toanode ears. The severance of the anode cars from their leads involves acutting of the anode leads, thereby shortening the portions of suchleads remaining in the severed stem. The shortened leads would be usedto engage the anode ears in the repaired mount. As a result the spacingbetween the cage and stem of the mount would be reduced. Such reducedspacing would require a commensurate modification in the lengths of theother leads in the stem, for appropriate engagement with other cageelements. Such length modification, in turn, would involve a new stemforming operation to bend the shortened leads to desired shape. The costof performing these operations on a stern after severance thereof fromthe cage would be such that it would be economically preferable to scrapthe entire defective mount.

In addition to this unfavorable cost relation, is the fact that aseverance of the anode lead-ins would leave short lengths of the lead-inwires welded to the ears of the anode. This would interfere with thesubsequent welding of the shortened lead-ins or the lead-ins in anotherand new stem, to the anode ears. And finally, a use of the stem havingthe shortened lead-ins, would lower the position of the cage on themount, to a degree that might be adverse to proper operation of theeventual electron tube. It is thus apparent that the increased handlingof the cage and stem during salvage operations would be prohibitive inlabor cost and result in a port salvage yield.

Accordingly, it is an object of the invention to provide an improvedelectron tube and method of making the same.

Another object of the invention is to provide a method of tubefabrication that includes an improved technique for salvaging a tubemount in which one or more parts thereof have been damaged.

A further object of the invention is to provide an improved method ofsalvaging an electron tube mount when a cathode heater and/ or aheater-cathode spacer employed therein, have been damaged.

According to one method of the invention, when a visual inspection of amount reveals that insulation has inadvertently been removed from eitheror both of the heater and spacer, at regions thereof where electricalshorts to the cathode are likely to occur, the heater and spacer areremoved from the mount without adversely affecting the remainder of themount. The removal is accomplished by severing the legs of the heaterand the spacer from their associated lead-ins and stud, and then pullingthe heater and spacer from the cathode end remote from the stem. Thespacer leg is severed at a region thereof sufliciently close to thecathode axis to prevent obstruction by the spacer leg to the removal ofthe spacer from the cathode.

According to another method of the invention, a new heater and spacerare inserted into the cathode in a novel manner. The insertion iseffected at the cathode end remote from the stern, since access to theother end of the cathode is obstructed by the stem. Before the heaterand spacer are inserted into the cathode, they are assembled bythreading the heater through the helical spacer, so that the legs of theheater extend from one end of the assembly, and the bent leg portion ofthe spacer extends from the other end. The assembly is inserted into theaforementioned remote end of the cathode, with the said one end of theassembly from which the heater legs extend, leading. After a fullinsertion of the heater-spacer assembly into the cathode, the bare legsof the heater protrude from the cathode end adjacent to the stem, andthe bare bent end portion of the spacer protrudes from the other end ofthe cathode. The protruding heater legs are then Welded to theirassociated lead-ins. The short lengths of the previously welded heaterlegs remaining on these lead-ins, do not interfere, because of theirrelatively small cross-sections, with the Welding of the lead-ins to thelegs of the new heater. The bent leg portion of the spacer is welded toa clip anchored in a novel manner in an electrode spacing wafer engagingthe end portion of the cathode remote from the stem. In this way, it isfeasible to insert a new heater-spacer assembly into the cathode withoutthe need to extend the laterally projecting bare leg end portion of thespacer through the cathode.

Further objects and features of the invention will become apparent asthe present description continues.

In the drawing, to which reference is now made for an example accordingto the present invention:

FIG. 1 is a side elevation of an electron tube mount in which asalvaging operation according to the invention, may be performed;

FIG. 2 is a longitudinal cross-section of an assembly comprising atubular cathode, a folded heater within the cathode, and an insulatedhelical spacer between the cathode and heater, employed in the tubemount shown in FIG. 1;

FIG. 3 is a longitudinal transverse view of an assembly of parts similarto that shown in FIG. 2 but in which the parts are arranged in a novelmanner to provide a salvaging operation in accordance with theinvention;

FIG. 4 is a top view of an electron tube mount salvaged in accordancewith the invention;

FIG. 5 is a side view partly in section taken along the line 55 of FIG.4 and rotated 90, of a clip anchoring an end of a helical spacer in asalvaged mount; and

FIG. 6 is a side view of the clip prior to insertion into an insulatingwafer.

In FIG. 1 the mount of an electron tube includes a stem 10 made ofglassfor example, and having lead-in wires extending therethrough. Theportions 12 through 18 of the lead-in wires extending above the stem 10as viewed in FIG. 1 are relatively thick, i.e. 30 mils, for preservingtheir initially formed positions in the mount and to provide ruggedsupports for the cage to be described. The portions 20 through 26 of thelead-in wires extending below the stem 10 engage contact prongs in abase, not shown. In addition to the lead-ins referred to, two studs 28,30 are anchored in the stem and extend from the upper face thereof only,for support purposes.

The electrode cage portion of the mount includes a tubular anode 33having side wings or flanges 34, 36 provided with cars 38, 40, 42 and 44extending through two 7 ample.

spaced insulating wafers 46, 48, for support thereby. Within the anode33 is disposed a tubular cathode 50 extending snuggly through openingsin the wafers 46, 48 and kept in desired position by means ofembossments 52, 54. The cathode 50 has an emitting coating SI thereon(FIG. 2) of conventional composition. Within the cathode is disposed afolded tungsten heater 56 having thereon an insulating coating 58 ofaluminum oxide, for ex- The heater wire 56 has a minimum thickness of2.5 mils. Bare end portions 60, 62 of the heater are welded to lead-inportions 14, 16. Between the inner wall of the cathode 50 and the foldedheater. 56 is dis- 7 posed a helical spacing member comprising a wire 64made of tungsten for example, and having a thickness of 5 mils. Aninsulating coating 66 is provided on the wire 64. This coating may bemade of aluminum oxide. The lower end portion of the spacer 64 as viewedin FIGS. 1 and 2 is bent laterally away from the axis of the cathode forconvenient welding of the bare portion 68 thereof, to stud 28. It willbe noted that this requires that the bent portion of the spacer extendlaterally appreciably beyond the lower end of the cathode 50. The anodeears 38, (FIG. 1), are welded to lead-in 12 and stud 30.

This lead-in and stud constitute a major support for the electrode cage.To the lower end portion of the cathode is welded a connector tab 69which is bent into engagement with lead-in portion 18 and to which it iswelded.

In the mount structure described, adequate insulation is provided on theheater 56 and the spacer 64 to electrically isolate'the cathode 50 fromthe heater. However, as a consequence of the need to deflect the heaterlegs 60, 62 into engagement with their associated lead-ins and.

to urge a welding tool against them in welding the legs to the lead-ins,the portion of the heater insulation im-.

mediately above thelegs thereof as viewed in FIGS. 1

and 2, may be brought into forceful engagement with the lower edge 70 ofthe cathode. This edge is relatively sharp and a forced engagementtherewith of insulated portions of the heater sometimes causes theinsulation to chip from the heater. Such chipping exposes the heaterwire and may result in electrical shorts between the heater and thecathode.

In a similar way, the insulation 66 on the lower end portion of thespacer 64 may also be chipped off by engagement of this portion with therelatively sharp lower edge of the cathode 50. While the lower endportion of the spacer 64 is bent laterally before it is assembled in themount, it usually requires some axial rotation thereof to bring it intoengagement with its stud 28. Such axial rotation and particularly whenfurther accompanied by a thrust on the bare end portion of the spacer bya welding tool during a welding operation, sometimes results in the'application to the coating '66 'by the lower edge 70 of the cathode 50,of a sufiiciently large force to chip the insulation from the spacer.While such loss of insulation might have no immediate effect, it woulddefeat the purpose for which the spacer is provided. This purpose is toincrease the insulation between the cathode 50 and the heater 56 bymeans of the insulating coating on the spacer.

This supplemental insulation is desirable in rectifier tubes of the typeillustrated, wherein the cathode and heater may be operated at a voltagedifference of at least 4400- volts.

When such loss of insulation occurs in a mount, salvaging thereof hasheretofore been considered impractical and the mount has been scrapped.This has 'been due in This" fore precluded insertion of the spacerthrough the upper end of the cathode.

Such preformed lateral extension is desirable in order to avoid applyingany appreciable bending stress to the spacer after its incorporation ina mount. Due to the relatively rugged character of the spacer, bendingstress applied after extending the spacer 64 into the cathode 50, wouldrequire such forceful engagement between the spacer and the lower edge70 of the cathode 50, as to prohibitively increase incidents of coatingloss from the spacer.

When a heater 56 or spacer '64 is seen to have insulation chippedtherefrom after these elements have been assembled in a mount, theheater and spacer are removed. In effecting such removal the legs of theheater and spacer are severed. The heater and spacer are then pulled, orremoved, from the end of the cathode remote from the stem. After suchremoval, a new heater and spacer on which the insulation is intact, areassembled in a novel manner prior to extension into the cathode (FIG.3). The assembling of the new heater 56 and spacer 64 involves threadingthe heater axially through the spacer, so that the legs 60, 62 of theheater extend from one end of the assembly and the laterally extendingleg 68 of the spacer protrudes from the other end of the assembly. Theassembly is then inserted into the cathode 50 by being initiallyextended into the cathode end remote from the stem 10, and with theheater leg end of the assembly in leading position.

A complete insertion operation exposes the heater legs at the stem endof the cathode, as shown in FIG. 3. The exposed heater legs are thendeflected into engagement with their associated lead-ins and weldedthereto.

A complete insertion operation also leaves exposed from the end of thecathode remote from the stem 10, the laterally extending leg 68 of thespacer 64. For supporting the spacer, a novel clip 72 is fixed to theinsulating wafer 46 remote from the stem, andto which the bare legportion 68 of the spacer is Welded, as shown in FIGS. 3 and 4. Since theclip 72 has utility only in salvaged mounts, it is desirable foreconomic reasons to provide the clip only in association with a mountsalvaging operation. However, since such operation takes place withrespect to a mount that is complete exceptfor the heater and spacer, amounting of the clip 72 on wafer 46 is accomplished in such a way as toavoid damage to the wafer. Both the wafer 46 and the clip 72 arestructurally designed to contribute to the preservation of the waferfrom harm during the clip mounting operation.

During fabrication of the initial mount shown in FIG. 1, the upper wafer46 is provided with two slots 74, 76, as depicted in FIG. 4. Each slotextends to an edge of the wafer to permit a lateral insertion of a clip72 thereinto. The slots are disposed in closely spaced relation withrespect to the cathode 50 to permit the lateral extension 68 of thespacer 64 to engage the clip when mounted in the slot. The slots arelocated at opposite edge portions of the wafer 46, and therefore arespaced 180 about the cathode 50. I

The presence of the two slots and their orientation limits the amount ofrotation required of the spacer 64 for engagement with the clip 72. Itwill be seen that if the clip is mounted in a slot closest to theinitial position of the lateral portion 68 of the spacer 64, the maximumamount of rotation of the spacer 64 needed for engagement of its lateralportion 68 with'the clip, is through an arc of 90. With one slot only,in the wafer 46, the maxi mum rotation required'of' the spacer 64 wouldbe through an arc of 180. This reduced magnitude of rotation of thespacer for engagement with the clip 72 is of appreciable advantage inpreserving the new spacer from coating loss.

The clip 72 has a structure that permits a mounting thereof on the wafer46 in an operation involving reduced stress on the wafer. The clip ismade of sheet metal such as nickel in ribbon form. It has a relativelysmall elastic limit, so that it preserves a shape to which it is formedby a tool. In its initial form, the clip is shaped to form four sides77a, 77b, 77c and 77d defining a closed structure and two legs 78, 80,shown in FIG. 6. The legs include portions 82, :84 which extend inparallel contacting relation from the closed portion of the clip, adistance substantially equal to the thickness of the wafer 46.

The clip 72 in its initial form as shown in FIG. 6 is inserted into oneof the slots 74, 76 closest to the lateral end portion 68 of the spacer64. After such insertion one portion of a clamping tool (not shown) isinserted into the closed space defined by the clip, and a cooperatingportion of the tool is disposed in engagement with the lower surface oflegs 78, 80. The two portions of the tool referred to are then urgedtoward each other resulting in a flattening of sides 77c and 77d of theclip against the upper surface of wafer 46, as shown in FIG. 5. Theforce applied is sufiicient to cause a portion of the wafer to be firmlyclamped between the legs 78, 80 and the sides 770 and 77d of the clip.

The initial structure of the clip 72, as shown in FIG. 6, is ofappreciable advantage in inserting the clip into a slot 74, 76 in thewafer 46, and in clamping it into a secure engagement with the wafer.The contacting leg portions 82, 84 have a composite thickness slightlyless than the width of either of grooves 74, 76, and a length slightlygreater than the thickness of the wafer 46. Each slot 74,76 has a depthdimension slightly larger than the width of the clip 72. Thesedimensions, coupled with the outward flare of clip sides 77c and 77dfrom the coplanar legs 78, 80, contribute to facility in fully extendingthe clip into one of the slots 74, 76 in the wafer 46. The subsequentclamping operation is aided by the initial coplanar disposition of thelegs 78, 80. Such disposition prevents the clip from moving upwardlywith respect to the wafer 46 during the clamping step. Downward movementof the clip with respect to the wafer in a clamping operation, isprevented by engagement between the flared sides 77c, 77d adjacent tothe leg regions 82, 84, and the upper surface of the wafer 46. Thus,when the clip is fully extended into a slot and when the flared sides77c, 77d are clamped against the upper surface of wafer 46 and intocoplanar relation, the clip is in proper position on the wafer.

After the clip has been clamped to the wafer 46, the spacer 64 isrotated in a direction to cause its bare end portion 68, now extendingabove the wafer 46, to engage a side, for example side 77b, of the clip72 and to which it is then welded.

This completes the salvaging operation. A mount so salvaged may now befurther processed, as by enclosure in an envelope, evacuation of theenvelope, and basing, for completion of an electron tube.

What is claimed is:

1. Method of making an electron tube mount comprismg:

(a) assembling a cage including a tubular cathode,

(b) fixing one end portion of said cage to a stem having lead-insextending therethrough, whereby a first end of said cathode is adjacentto said stem,

(c) inserting through the second end of said cathode, an assemblycomprising an insulated heater having a bare leg and an insulatedhelical spacer member surrounding said heater, to cause said leg of saidheater to protrude from said first end and a portion of said spacer toprotrude from said second end of the cathode,

(d) fixing said heater leg to a lead-in extending through said stem, and

(e) fixing said portion of said spacer to a support on said cage.

2. Method of making an electron tube mount comprismg:

' (a) assembling a cage including a tubular cathode,

(b) fixing one end portion of said cage to a stem, whereby a first endof said cathode is adjacent to said stem,

() inserting a heater and spacer assembly through the second end of saidcathode, to cause leg portions of said heater to protrude from saidfirst end and a leg portion of said spacer to protrude from said secondend of the-cathode,

(d) fixing said heater leg portions to lead-ins extending through saidstem, and

(e) fixing said spacer leg to a support on said cage.

3. Method of making an electron tube mount, compris- (a) assembling acage having an insulating water at one end thereof, and including atubular cathode,

(b) mounting a clip on said wafer,

(c) fixing the other end portion of said cage to a stern having lead-insextending therethrough, whereby a first end of said cathode is adjacentto said stern,

(d) inserting a heater and spacer assembly through the second end ofsaid cathode, to cause leg portions of said heater to protrude from saidfirst end and a leg portion of said spacer to protrude from said secondend of the cathode,

(e) fixing said heater leg portions to lead-ins extending through saidstem, and

(f) fixing said spacer leg to said clip.

4. In a method of making an electron tube mount,

the steps comprising:

(a) fixing one end portion of a cage having a tubular cathode, to astem, to dispose a first end of said cathode adjacent to said stem, and

(b) inserting through the second end of said cathode, an assemblycomprising an insulated heater having a bare leg and an insulatedhelical spacer member surrounding said heater, to cause said leg of saidheater to protrude from said first end and a portion of said spacer toprotrude from said second end of the cathode.

5. Method of making an electron tube mount comprising:

(a) forming an elongated insulated heater structure having a bare legextending from one end thereof,

(b) forming an insulated wire to helical structure,

(c) inserting said heater structure axially into said helical structure,to form as assembly wherein said bare leg extends from one end of theassembly and one end portion of the helical structure extends from theother end of the assembly,

(d) fixing an electrode cage having a tubular cathode to a stem, whereinone end of said cathode is adjacent to said stem,

(e) inserting said assembly into said cathode from the other end of thecathode, with said bare leg of the assembly leading, to cause said legto extend from said one end of the cathode and said one end portion ofthe helical structure to extend from the other end of the cathode,

(f) fixing said heater leg to a lead-in in said stem,

and

(g) fixing said one end portion of the spacer to a support on said cage.

6. Method of making an electron tube mount comprising:

(a) forming an elongated insulated heater structure having two bare legsextending from one end thereof,

(b) forming an insulated wire to helical structure, with an end portionthereof free of insulation,

(c) inserting said heater structure axially into said helical structure,to form an assembly wherein said bare legs extend from one end of theassembly and said end portion of the helical structure extends from theother end of the assembly,

(d) fixing to a stem an electrode cage having a tubular (f) fixing saidheater legs to lead-ins extending through said stem, and (g) fixing saidbare end portion to a support on said cage. 7. Method of replacing afolded insulated heater and a helical insulated spacer in a tubularcathode in an electron tube mount, comprising:

(a) severing leg portions of said heater and spacer,

(b) removing said heater and spacer member from said cathode,

(c) forming an'assembly of another heater and spacer by threading thenew heater axially through the new spacer to cause bare legs of the newheater to extend from one end of the assembly and to cause a leg of thenew spacer to extend from the other end of the assembly,

(d) extending said assembly through said cathode to cause said bareheater legs to protrude from said one end of the cathode and to causesaid spacer leg to protrude from the other end of the cathode,

(e) fixing said heater legs to conductors in said mount,

(f) fixing a clip to said mount remote from said conductors, and

.- (g) fixing said spacer leg to said clip.

8. Method of salvaging an electron tube mount having a faulty assemblywithin a tubular cathode, wherein said assembly comprises a foldedinsulated heater, and a helical insulated spacer between said heater andthe inner wall of said cathode, said heater and spacer having legportions extending from said one end of the cathode and fixed to a stemsaid method comprising:

(a) severing said leg portions, 7 (b) pulling said heater and spacermember from said cathode,

(c) forming an assembly of a new heater andspacer by threading the newheater through the new spacer to cause bare legs of the heater to extendfrom one end of the assembly and to cause a leg of the spacer to extendfrom the other end of the assembly,

(d) extending said assembly through said cathode to cause said bareheater legs to protrude from one end of the cathode adjacent to saidstem and'to cause said spacer leg to protrude, from the other end of thecathode,

(e) fixing said heater legs to conducting wires in said stern,

(f) fixing a clip adjacent to said other end of the cathode, and

(g) fixing said spacer leg to said clip.

9. Method of salvaging an electron tube mount having a tubular cathodesupportedby an insulating wafer, an assembly within said cathodecomprising a folded insulated heater and a helical insulated spacerbetween said heater and the inner wall of said cathode, and a stemadjacent to one end of said cathode and having conducting wires fixed toleg portions of said heater and spacer that are bare of insulation andthat extend from said one end of the cathode, said method comprising:

. (a) severing said leg portions of said heater and spacer,

(b) pulling said heater and spacer member from the other end of saidcathode,

(c) forming an assembly of a new heater and spacer by threading the newheater through the new spacer to cause a bare leg of the heater toextend from one end of the assembly and to cause a leg of the spacer toextend from the other end of the assembly,

( extending said assembly through the other end 9 of said cathode tocause said bare heater leg to protrude from said one end of the cathodeand to cause said spacer leg to protrude from the other end of thecathode,

(e) fixing said heater leg to one of said conducting wires,

(f) fixing a clip to said wafer to cause a portion of said clip toextend from a face of said wafer remote from said stem,

(g) fixing said spacer leg to said portion of the clip.

10. Method of salvaging an electron tube mount having a tubular cathodesupported by two spaced insulating wafers, an assembly within saidcathode comprising a folded insulated heater and a helical insulatedspaced between said heater and the inner wall of said cathode, and astem adjacent to one end of said cathode and having conducting wiresfixed to leg portions of said heater and spacer that are bare ofinsulation and extend from said one end of the cathode, said methodcomprising:

(a) severing said leg portions adjacent to said conducting wires,

(b) removing said heater and spacer member from the other end of saidcathode,

(c) forming an assembly of a new heater and spacer by threading the newheater through the new spacer to cause bare legs of the heater to extendfrom one end of the assembly and to cause the bare leg of the spacer toextend from the other end of the assembly,

(d) extending said assembly through the other end of said cathode tocause said bare heater legs to pro trude from said one end of thecathode and to cause said bare spacer leg to protrude from the other endof the cathode,

(e) fixing said heater legs to two of said conducting wires,

(f) fixing a clip to one of said wafers adjacent to said other end ofthe cathode, and

(g) fixing said spacer leg to said clip.

11. Method of salvaging an electron tube mount including a stem and anelectrode having an insulating wafer adjacent to the end of the cageremote from said stem, said wafer having -a slot extending to one edgethereof, said method of comprising:

(a) removing a defective part from said mount,

(b) inserting in said slot a clip having coplanar legs extending inopposite directions, with said legs engaging the inner face of saidwafer, and with a support region of said clip extending from the outerface of said wafer,

(c) flattening a portion of said support region against the outer faceof said wafer,

(d) mounting a substitute part for said defective part in said mount,and

(e) fixing said substitute part to said support region of said clip.

12. Method of salvaging an electron tube mount including a stern havinglead-ins extending therethrough and a cage assembly supported on saidlead-ins and including a tubular cathode and a pair of spaced insulatingwafers between which said cathode is supported, a heater and aninsulating spacer around said heater, said heater and spacer beingwithin said cathode, one of said spacers having a 10 slot extending fromone edge thereof, said method comprising:

(a) removing a defective part from said mount, (b) inserting a clip insaid slot, 5 (c) mounting a substitute part for said defective part insaid mount, and

(d) fixing said substitute part to said clip.

13. Method of salvaging an electron tube mount comprising:

(a) removing a defective part from said mount,

(b) loosely mounting on an insulation water of said mount a clip havingcoplanar legs extending in opposite directions, with said legs engagingthe inner face of said wafer, and with angularly diverging sides of saidclip extending from said outer face of said water,

(c) flattening said angularly diverging sides tightly against the outerface of said Wafer,

(d) mounting a substitute part for said defective part in said mount,and

(e) fixing said substitute part to said clip.

14. Method of mounting a clip on an insulating wafer forming part of anelectron tube mount, comprising:

(a) forming a sheet metal strap to define a four-sided closed structurehaving two legs extending from the junction of two of the sides thereof,said legs including parallel portions adjacent to said structure and incontacting relation, said parallel portions having a length slightlymore than the thickness of said wafer, said parallel portions having aWidth slightly less than the depth of said slot, said legs including endportions extending in opposite directions in a common plane, said twosides of said structure defining an angle of less than 45 with respectto said plane,

(b) inserting said parallel portions of said clip into said slot,whereby said leg end portions engage in inner face of said spacer, and

(c) flattening said two sides of the clip against an outer face of saidspacer for clamping a portion of said spacer between said two sides andsaid leg end portions.

15. Method of making an assembly comprising an elongated foldedinsulated heater structure having bare legs at one end of the structureand an insulated helical spacer 45 structure having a bare leg at oneend, said method comprising:

(a) supporting said spacer structure in a position wherein said bare endthereof extends in one direction, and (b) threading said heaterstructure into said spacer structure to cause the bare legs of theheater structure to extend in a direction opposite to said onedirection.

References Cited by the Examiner UNITED STATES PATENTS 1,872,344 8/1932Robinson 2925.15 2,532,846 12/1950 Jonker 2925.15 2,815,465 12/ 1957Shelton 313-337 2,870,366 1/1959 Van Tol 313337 RICHARD H. EANES, JR.,Primary Examiner. D. I. GALVIN, Examiner.

10. METHOD OF SALVAGING AN ELECTRON TUBE MOUNT HAVING A TUBULAR CATHODESUPPORTED BY TWO SPACED INSULATING WAFERS, AN ASSEMBLY WITHIN SAIDCATHODE COMPRISING A FOLDED INSULATED HEATER AND A HELICAL INSULATEDSPACED BETWEEN SAID HEATER AND THE INNER WALL OF SAID CATHODE, AND ASTEM ADJACENT TO ONE END OF SAID CATHODE AND HAVING CONDUCTING WIRESFIXED TO ONE LEG PORTIONS OF SAID HEATER AND SPACER THAT ARE BARE OFINSULATION AND EXTEND FROM SAID ONE END OF THE CATHODE, SAID METHODCOMPRISING: (A) SEVERING SAID LEG PORTIONS ADJACENT TO SAID CONDUCTINGWIRES, (B) REMOVING SAID HEATER AND SPACER MEMBER FROM THE OTHER END OFSAID CATHODE, (C) FORMING AN ASSEMBLY OF A NEW HEATER AND SPACER BYTHREADING THE NEW HEATER THROUGH THE NEW SPACER TO CAUSE BARE LEGS OFTHE HEATER TO EXTEND FROM ONE END OF THE ASSEMBLY AND TO CAUSE THE BARELEG OF THE SPACER TO EXTEND FROM THE OTHER END OF THE ASSEMBLY,